1. Field of the Invention
The present invention relates to a method and apparatus for controlling operation of lamps, and a backlight assembly and liquid crystal display device having the same. More particularly, the present invention relates to a method and apparatus for controlling operation of lamps in which temperatures of the external electrodes of the lamps are detected and controlled to be lower than a threshold temperature on which pinholes are generated.
2. Description of the Related Art
Liquid crystal display (LCD) devices include a liquid crystal (LC) panel to display images and a backlight assembly disposed on a rear portion of the LC panel to supply light to the LC panel. Backlight assemblies are classified into an edge type and a direct type according to the position of a light source.
Edge type backlight assemblies have light sources disposed at an edge portion of an LC panel, and are used in smaller sized LCD devices such as laptops or desktop computers. Edge type backlight assemblies have superior light uniformity and endurance life and allow LCD devices to be slimmer. Direct type backlight assemblies have a plurality of lamps arranged in parallel under a diffusing plate, and supply light to the entire surface of LC panel. Direct type backlight assembles have superior luminance, and are used in larger LCD devices. External electrode fluorescent lamps (EEFLs), which have improved light efficiency and reduced manufacturing cost as compared with cold cathode fluorescent lamps (CCFLs), are used for direct type backlight assemblies.
FIG. 1 is a schematic view illustrating a method for controlling the operation of an EEFL employed in a backlight assembly. A sensor 10 and a control circuit 14 determine together whether the EEFL 12 is turned on/off, and control the operation of an inverter 16. For example, when the sensor 10 and the control circuit 14 determine that the EEFL 12 is turned off, a shutdown signal is applied to the inverter 16, thereby forcibly shutting down an electrical power provided to the EEFL 12.
The shutdown method, however, shutdowns a backlight assembly after the EEFL 12 is turned off. That is because pinholes are generated in the EEFL 12. Further, when a plurality of EEFLs is disposed to be closer to each other or the sensor 10 is disposed farther away from the EEFL 12, it is not easy to determine whether an individual EEFL 12 is turned off or not. Furthermore, because there are other factors that could affect the determination such as a condition of lamp, a distance between the lamp and the sensor, a structure of a metal device, etc, the shutdown method is not reliable.